Apparatus for electrically measuring the wall thickness of metal tubing and for controlling the wall thickness



Sept. 10, 1940. F, H' GOODING 2,213,983

APPARATUS FOR ELECTRICALLY MEASURING THE WALL THICKNESS 0F METAL TUBING AND FDR CONTROLLING THE WALL THICKNESS Filed July 12, 1938 6 Sheets-Sheet 1 f IIVENTIOR W ATTORSEYS'.

Sept. 10 1940. F. H. sooome 2,213,983

APPARAT FOR ELECTRICALLY MEASURING THE WALL THICKNESS 0F METAL TUBING AND FOR CONTROLLING THE WALL THICKNESS Filed July 12, 1938 6 Sheets-Sheet 2 Fig. 4.

INVENTOR W ATTORNEY.

p 0, 1940. F H. GOODING 2,213,983

APPARATUS FOR ELECTRICALLY MEASURING THE WALL THICKNESS OF METAL; TUBING AND FOR CONTROLLING THE WALL THICKNESS Filed July 12. 1938 6 Sheets-Sheet 3 fig 5.

g FINVENTIZOR I Sept. 10, 1940. F. H. aooomc 13, APPARATUS FUR ELECTRICALLY MEASURING THE WALL THICKNESS OF METAL TUBING AND FOR CONTROLLING THE WALL THICKNESS Filed July 12, 1938 6 Sheets-Shad. 4

\NVENTOR MMM Sept. 10, 1940. F. H. soonme 2,213,983 APPARATUS FOR ELECTRICALLY MEASURING THE WALL THICKNESS OF METAL TUBING AND FOR CONTROLLING THE WALL THICKNESS Filed July 12, 1938 S Sheets-Sheet 5 \NV NTOR' TTORNEYS- v Sept. 10, 1940- F H. GOODING 2,213,983

APPARATUS FOR ELECTRICALLY MEASURING THE WALL THIdKNESS 0F METAL TUBING AND FOR CONTROLLING THE WALL THICKNESS Filed Jqly 12, 1938 6 Sheets-Sheet 6 M aVENT QR Patented Sept. 10, 1940 PATENT OFFICE 2,213,983 "APPARATUS FOR ELECTRICALLY MEASUR- ING THE WALL TUBING AND WALL THICKNESS Francis H.

Gooding, Lodi,

THICKNESS OF METAL FOR CONTROLLING THE N. J., assignor to The Okonite-Callender Cable Company, Incorporated, Paterson, Jersey N. J., a corporation .of New Application July 12, 193&, Serial No. 218;136

6 Claims.

This invention is directed to improved equipment for electrically measuring the wall thickness of tubular members and to equipment for the promotion of the production of tubular members of constant thickness around the circumference.

While my invention is adapted for electrically measuring the wall thickness of all types of metal tubing, it is particularly well adapted for electrically measuring the wall thickness of cable sheaths, and for clarity of description will be described in this connection.

It might be pointed out that in the sheathing of electric cables, for example, not only is it desirable that the sheath wall be of constant thickness around the sheath circumference, but the buyers of such equipment specify a minimum thickness, and it is not unusual under present practice to find some point in the cable where the thickness of the sheath may be as much as 15% or 20% below the minimum specified. instance, a 125 mil sheath can easily run down to 100 mils at some point in the sheath circumference, so that the sheath-is then no stronger than if the whole sheath were 100 mils thick. Inasmuch as these thin areas but rarely occur at the ends of the cable their existence is readily overlooked.

The present invention provides for continuously indicating and recording sheath conditions so far as wall thickness is concerned as the sheath is being manufactured. V

One embodiment of my invention provides for the continuous indicating and recording of per cent variations from an average thickness at a plurality of points about the sheath periphery; an extension of this idea provides for continuously indicating and recording differences in sheath thickness at opposite points on the sheath periphery; still another embodiment of my inindicating and recording actual sheath thickness at about the sheath periphery; while a further extension of my invention not only provides for indicating, and recording actual sheath thickness but provides, also, for the automatic control of the heating of the die block of the lead press so as to produce a sheath the wall of which is of uniform thickness about the circumference of the sheath throughout the entire sheath length.

In the accompanying drawings:

Fig. l is a part sectional elevational view of an exciting coil constituting part of the equipment used in the practice of my invention;

Fig. 2 is a half view of the left hand end of the apparatus of Fig. 1;

Fig. 3 is a sim'lar view of the right hand end of the apparatus of Fig. l; I

Fig. 4 is a wiring diagram or layout of one embodiment of my invention wherein I continuously indicate and record per cent variations from an average wall thickness;

Fig. 4 is simply an enlarged view of the face of one of the indicating and recording potentiometers shown on Fig. 4;

v Fig. 5 is a wiring diagram or layout of that embodiment of my invention wherein I continuously indicate and record differences in wall thickness at opposite points on the sheath periphery; r

Fig. 6 is a wiring diagram or layout of an embodiment of my invention wherein I continuously indicate and record plurality of points about the sheath periphery;

Fig. '7 is a diagram of an arrangement whereby the heating of the lead press may be automatically controlled; and

Fig. 8 is a wiring diagram the arrangement shown in Fig. 5, for example.

Referring to the drawings in detail and first of all to the embodiment of my invention illustrated in Figs. 1 to 4 inclusive.

My improved apparatus coil 2 carried in end plates concentrically with respect to metal sheath or other tubular member 8, the coil from the sheath by four rollers l0 mounted on a plate 12 at one end of the coil and by four slides l4 mounted on the plate 6 at the other end of the coil.

The rollers H) are carried by brackets l6 capable of being individually adjusted by knurled screws l8 properly to center the coil with respect to the tube 8. The slides l4 may also be individually adjusted by knurled screws 20.

The coil assembly, in practice, is hung from a pulley and counterbalanced with a suitable weight. sheath marking as well as wear on the rollers. I also propose to anchor the coil against forward movement with suitable anchoring means such as a heavy wire which may be hooked to the frame of a lead press, for instance.

It will be understood that the rollers l0 and slides M are for the purpose of steadying the coil and for maintaining the coil 2 concentric with the sheath 8.

The exciting coil carries four pairs of contacts 22 which continuously contact the sheath when 4 and 6 and mounted of a modification of I comprises an exciting being spaced This facilitates handling and reduces my equipment is in operation.

tacts is mounted on a holder 24 attached to a strip 26, each of these strips being fastened to a bracket on theroller assembly.

Pressure is appliedto each pair of contacts by means of a steel wire 28 which is v roller end of the coil and passes through at frame 30 above each set of contacts and through a strip 32 at the slide end of the coil. The strip 32 Each pair of congood contact on the cable It will be understood, of course, that the contacts are intermediate the coil the contacts are-closely twisted, drawn into tubing and finally run into a ring shaped pipe 36 at the roller end of the coil.

The coil 2 is excited from any suitable source of power, as shown at 38 on the wiring diagram of Fig. 4, as for example a source of 220 volt 60 cycle alternating current.

Referring now more diagram of Fig.

transformers can conveniently be the bracket which supports the coil.

The voltage output of the transformer 48 goes to a bridge type rectifier designated 56 which is connected across the transformer secondary; the output side of the The rectifiers 56, 58, 60 and 62 are connected in turn to indicating and recording potentiometers 64, 66, 68 and 10, respectively.

The theory of operation of my invention is based on the unequal distribution of potential current power supply 38.

It will be apparent that if the advancing tubing or sheath 8 is of uniform thickness, as the the potential induced in the section of sheath lying between the contacts 40 will be equal to that induced in the section of sheath lying be sheath it is absorbed non-uniformly, then it will able to that is to say, is not of uniform wall thickness around the circumference of the sheath. The potentiometers will be marked, for example side, left side,

ings as have been. employed in connection with Fig. 4.

With reference to the diagram of Fig. 5, the sheath 8 is surrounded by a coil 2 the same as in Fig. 4. Contacts 40 rest upon the upper side of the sheath 8; contacts 42 upon the right hand side of the sheath; 44 upon the lower side of the contacts 44 is too light or too thin. The operator can then adjust the heating elements of his lead press accordingly.

Likewise with respect to the potentiometer I8 movement of the indicating element 82 to the right indicates that the section of the sheath between the contacts 42 is too light or too thin and movement of this element to the left indicates that the section of sheath between the contacts 46 is too light or too thin.

With this embodiment of my invention, due to the fact that one potentiometer is connected through two rectifiers which are connected in opposition to each other and in turn connected across the secondary of two separate transformers, one of which transformers is connected to the contacts 48 at the top of the sheath, the other to contacts 44 at the bottom of the sheath, a reading will be obtained on the potentiometer 14 by reason of a diiference in thickness between a section of the sheath lying between the contacts 48- and the section of the sheath at the bottom lying between the contacts 44. For the same reason the poteniometer 18 will indicate and record a difference in thickness between a section of the sheath lying between the contacts 42 at the right hand side of the sheath and the contacts 46 at the left hand side of the sheath.

In the arrangement just described it will now be apparent that the potentiometer I4 will indicate at any instant the difference in sheath thickness between top and bottom of the sheath, while the potentiometer 'I8 will give the same information at any instant with respect to the sheath thickness sheath. 8

In the embodiment of my invention illustrated in Fig. 6 I have provided an arrangement for indicating and recording actual thickness of the sheath at four points around the circumference of the sheath. In this arrangement I employ a master sheath which I will designate 84, the thickness of this master sheath, of course, being uniform.' This sheath will be surrounded by a coil 86 which is identical with the coil 2 surrounding the sheath 8, the two coils being connected in series and therefore carrying the same current. Contacting the sheath 84 are pairs of contacts 88, 88, 92 and 94at the top, right hand side, bottom and left hand sides, respectively, of the master sheath or pipe 84. As in the other embodiments of my invention already described, pairs of contacts 48, 42, 44 and 46 engage the sheath 8 at top, right hand side, bottom and left hand side, respectively. The contacts 88, 98, 92 and 94 of the master pipe 84 are connected to transformers 86, 98,- I88 and I82, respectively.

The secondary of each of these transformers is connected to a rectifier of the bridge type such as referred to in connection with Figs. 4 and 5, for instance, designated I84, I86, I88 and H8, respectively, and one side of these rectifiers is connected to potentiometers 64, 66, 68 and 18, respectively. All of these potentiometers 64, 66, 68 and '18, are of the recording and indicating type. The other side of the rectifier I84 is connected to one side of the rectifier 56 which is across the transformer 48 connected to the contacts 48, the other side of the rectifier 56 being connected to the potentiometer 64, the direction of the connections being such that the output voltages of the bridge rectifiers are in opposition. The other side of the rectifier I86 isconnected to one side of the rectifier 58 connected across at opposite sides-0f the the transformer other side of this rectifier 68 being connected to the potentiometer 66. Here again the direction of the connections is such that the output voltages of the bridge rectiflers are in opposition.

. 3 68101 the contacts 42; the,

The other side of the rectifier I88 is connected to one side of the rectifier- 68 connected across the transformer 52 for the contacts 44, the other side of this rectifier 68 being connected to the potentiometer 68, the output voltages of the two rectifiers being in opposition. The other side of the rectifier H8 is connected to one side of rectifier 62 across the transformer 54 for the contacts 46, the other side of this rectifier 62 being connected to the potentiometer l8, and the direction of the connections being such that the output voltages of the rectifiers are in opposition.

It will be apparent that with this arrangement the potentiometer 64 will indicate and record the difference in thickness between that part of the master pipe or sheath 84 lying between the contacts 88 and the thickness of that part of the sheath 6 lying'between-the contacts 48. It will be apparent also that with this arrangement the indicating and recording po-v tentiometers 64, 66, 68 and III will indicate and record the difference in thickness of the master sheath 84 and the sheath 8 at the right side, left side and bottom of the sheaths. It will be understood, of course, that the thickness of the master tubing or sheath is already known from micrometer measurements so that the potentiometers can be calibrated in mils thickness.

In the embodiment of my invention illustrated in Fig. 7 I have illustrated av construction wherein I propose automatically to control the heating of the die blockI I2 of a lead press when the invention is employed in connection with the extruding of lead sheaths. To avoid repetition and to simplify the drawings, 1 have shown in Fig. '7 two commutator switches H4 and H6 and these commutator switches are mounted on the main shafts H8 and I28, respectively, of the two potentiometers 14 and 18 of Fig. 5.

As above explained, the potentiometer 14 of Fig. 5 indicates a difference in sheath thickness at top and bottom while the potentiometer 18 indicates a difference in thickness between the sides of the sheath.

Adjacent the die block II2 of the lead press I provide gas nozzles I22, I24, I26, I28, I38 and I32. The nozzles I22 to I26 are connected through valve mechanism to gas line I34 which branches from a gas booster pump I36 connected to gas main I38. The nozzles I28 to I32 are connected to gas pipe I48 which also leads from the booster pump I36. The flow .of gas to the nozzles I22 and I26 is controlled by two valves I42 and I44 on the one valve stem which is adapted to be actuated by coil I46. The flow of gas to the nozzle I24 is controlled by a valve I48 which is adapted to be actuated by coil I58. The nozzle I22 is near the top of the sheath coming through the die block, the nozzle I24, at the right hand side of the sheath and the nozzle I26, near the bottom of the sheath. The nozzles I28, I38 and I32 are on the opposite side of the die block to the nozzles I22 to I26 and the flow of gas through the nozzles I28 and I32 is controlled by valves I52 and I54 on a single stem actuated by coil I56 while the flow of gasthrough the nozzle I38 is controlled by valve I58 actuated by coil I68. The valves I58 and I48 are operated independently of each other.

. I42, I52 and I58 are in .flow through the line I34, past the As the parts are shown in Fig. 7, the valves open position, the valves I44 and I48 being closed, so that gas can valve I 42 to the gas nozzle I22 which, as above noted, is near the top of the die block atone side of the die block. The valve I62 being open gas can also flow to the nozzle I28 which is in line with the nozzle I22 but on the opposite side of the die block. The valve I58 being open gas can also flow' to the nozzle I30which is at the left hand side of the die block about midway of the .same. This is the setting under an assumed condition where the left side and top of the sheath being extruded are too thin or too light, necessitating increasing the temperature of the die block at the top and the left side, it being understood,

of course, that by heating one point of the block more than another more lead will flow tothat point, so that the thickness of the extruded sheath becomes greater at that point. Under these conditions the shaft II 8 of the potentiometer 14 has moved to the left so that the commutator switch I I4 is rotated to close a circuit to the coils I46 and I56. The circuit for the I coil I56 may be .traced fromone side of the line, conductors I62, I64," switch segments I66, I68, conductors I10, I12, coil I56, conductors I14, I16, I18 to the other side of the line. 1

Energizing of the coil I56 will, of course, open the valve I52 so that gas can'fiow to the nozzle I28 at the left side of the die block near the top thereof, and at the same time 'close the valve I54 controlling theflow of gas to nozzle I32.

The circuit to the coil I46 may be traced by way of conductor I80, branching from the conductor I10, coil I46, conductors I82 and I84, I16, I18, to the other side of the line.

Energizing of the coil I46 opens the valve I42 so that gas can flow to the nozzle I22 to the right hand side of the die block near the top,

at the same time closing valve I44 controlling from the drawing itself in the opposite direction the flow of gas to nozzle I26.

The potentiometer 18 has moved the commutator switch II6 so that a circuit is closed at this time to the coil I60 for the valve I58. This circuit may be traced I86, switch segments I88, I90, conductors I92, I93, coil I60, conductors I94, I18, to the other side of the line. Gas is now free to fiow past the valve I58 to the nozzle I30.

It is believed that it is unnecessary to trace other circuits of this diagram; it being obvious that movement of the switches H4 and H6 by the potentiometers 14 and 18 will deenergize the coils I56, I46 and I60, closing valves I52 and I56 and opening valves I42, I54 and I44 to ad mit gas to nozzles I32 and I26. At the same time the coil I50 will be energized to admit gas to nozzle I24.

The embodiment of my invention illustrated in the fragmentary diagram of Fig. 8 is quite similarto the construction described in connection with Fig. 5.

Referring to thisembodiment of the invention: 8 designates the sheath or tubing and 2 the exciting coil surrounding the same. As in Fig. 5, contacts 40 and 44 are provided at the top and bottom, respectively, of the sheath, and contacts 42 and 46 at the right and left sides, respectively. In this embodiment of my invention tube rectiflers are substituted for the rectiflers 56, 60, 62 and 58 of Fig. 5. But two of these rectifiers have been shown, designated 56' and 60', correby way of conductors I62,

sponding to rectiflers of the sheath, respectively. The heating transformer for tube rectifier 56' is designated 200 and that for the rectifier 60' is designated 202.

The rectifiers 56' and 60 are connected to the transformers 48 and 52, respectively, and are also connected to each other similarly to the connection of rectifiers 56 and 60 to each other, that is to say, so that the voltage outputs of the rectiflers are in opposition, this voltage difierence being applied to the centrepoint potentiometer 14.

It will be understood that two other rectiflers similarly connected to each other and to the transformers connected to the contacts 42 and 46 are provided in this embodiment of my invention, these rectifiers being connected to the potentiometer 18. The tube rectifiers are run at low voltage and hence low filament emission. Emission currents are balanced before applying voltage to the coil 2. The use of tube rectiflers is of advantage as compared with the rectifier-s employed in Fig. 5 in that they do not deteriorate.

From all of the foregoing it will be seen that I have provided for the promotion of the production of tubular members of constant thickness around the circumference. It

the tubular-member isbeingformed.

It is to be understood that changes may be made in the details of construction and arrangement of parts herein illustrated and described within the spirit and scope of my invention.

What I. claim is:

1. Apparatus for detecting variations in wall thickness about the circumference of tubular metal members, comprising means for inductively circulating current circumferentially in the tubular member. and an electrically operated indicating device for indicating difierences in wall thickness at opposite points on the periphery of the tubular member.

2. Apparatus for detecting variations in wall thickness about ,the circumference. of tubular metal members, comprising means for inductivegagement therewith, transformers'connected to said contacts, a rectifier connected to the output side of each transformer, the rectifiers for opposed pairs of contacts being connected to each other so that their voltage outputs are opposed, and an indicating and recording device connected to each pair of rectifiers.

3. Apparatus of the class described, comprising in combination an extrusion press, heating elements therefor, and means actuated due to variations in the wall thickness of a tube being extruded from said press for controlling said 66 and to. top and bottom heating elements to correct said wall thickness.

4. Apparatus of the class described, comprising in combination an extrusion press for extruding a metal tube, heating elements for the press, indicating instruments for indicating variations in the wall thickness of the tube as the same is ling said heating elements.

5. Apparatus of the class described, comprising in combination an extrusion press for extruding a metal tube, heating elements, valves for controlling the fuel supply to said heating elements, instruments for registering variations in the wall thickness of the tube as the same is being extruded, and switches for controlling said valves,

therein for indicating variations in the wall thickness of the tube circumferentially of the tube, switches positively actuated by said instruments, and electrically operated valves controlled by said switches for controlling the operation of the heating elements thereby selectively to increase and decrease the heat applied to the press.

FRANCIS H. GOODING. 

